LED module, method for manufacturing the same, and LED channel letter including the same

ABSTRACT

A light emitting diode (LED) module including: a circuit board; at least one LED disposed on the circuit board; a molding cover spaced apart from the LED by a predetermined gap and covering upper and lower surfaces of the circuit board at an edge of the circuit board; and a circuit part positioned at the edge of the circuit board and driving the LED. The LED is centrally disposed on an upper surface of the circuit board.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation in part of U.S. application Ser. No.13/416,540, filed on Mar. 9, 2012, and claims priority from and thebenefit of Korean Patent Application No. 10-2011-0022034, filed on Mar.11, 2011, and Korean Patent Application No. 10-2011-0022035, filed onMar. 11, 2011, which are incorporated herein by reference for allpurposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

Field of the Invention

Exemplary embodiments of the present invention relate to a lightemitting diode (LED) module, a method for manufacturing the same, and anLED channel letter including the same.

Discussion of the Background

A cold cathode fluorescent lamp (CCFL), which is called a ‘fluorescentlamp,’ has been widely used as an illumination device for a long periodof time. However, the cold cathode fluorescent lamp has disadvantagessuch as a short lifespan, poor durability, a limited range of colorselection, and low energy efficiency.

A light emitting diode (LED) has several advantages such as excellentresponsibility, high energy efficiency, a long lifespan, and the like.In accordance with development of a high brightness and high output LED,the demand of the LED has rapidly increased as a light source forillumination or other light sources.

According to the related art, an LED module in which the LED is mountedon a circuit board such as a printed circuit board (PCB) has been known.A package level of LED, that is, an LED package has been typicallymounted on the circuit board. However, recently, an interest in a chiplevel of LED, that is, an LED module in which one or more LED chips aremounted on a circuit board has increased. In the LED module as describedabove, the circuit board and the LED mounted on the circuit board aresignificantly vulnerable to an external environment such as humidity,air, and the like. Therefore, a technology of protecting electrodes andLEDs on a circuit board from an external environment has been demanded.

A technology of covering a circuit board with a molding covermanufactured by injection-molding a plastic resin in a molding space ofa mold may be considered. Here, if a space is not present between abottom of the molding and the circuit board, the molding cover is formedonly on an upper surface of the circuit board. Therefore, even thoughthe molding cover is provided, the entire bottom surface and the entireside of the circuit board are exposed to the external environment.

As an alternative to the above-mentioned technology, a technology offorming pin holes in a circuit board and inserting pins installed on amold into the pin holes to position the circuit board at the centerwithin a molding space of the mold may be considered. In this case, amolding cover formed in the molding space covers a bottom surface of thecircuit board as well as an upper surface thereof. In this case, holesremaining after the pins are separated, that is, pin marks pass throughthe molding cover and are then connected to the pin holes of the circuitboard, and a route from the pin marks to the pin holes becomes a routethrough which external humidity and/or air penetrates.

SUMMARY OF THE INVENTION

Therefore, exemplary embodiments of the present invention suggest atechnology of providing an LED module having a structure in which pinholes formed in a circuit board are closed.

Recently, an illumination device formed by installing a plurality of LEDmodules in channels having a shape such as a letter, a logo, a symbol, anumber, or a sign has been developed. This illumination device is calledan ‘LED channel letter’.

In an existing LED channel letter, as a connection scheme of a powersupply or a circuit, a wire soldering scheme is mainly used. This schemerequires a manual operation to cause a process defect. In addition, whena problem occurs in only one LED module among several LED modulesinstalled in a channel, the entire product should be replaced.

According to the present invention, when an LED module having aconnector for connecting a power supply or a circuit is applied to anLED channel letter, in case a problem occurs in a specific LED module, achannel letter may be used by replacing only a corresponding LED module,which is economically practical. In addition, the LED channel letterrequires a complicated shape in implementing a letter, a logo, a symbol,a number, and/or a sign. However, an LED module only including only auni-direction connector or bi-directional connectors facing each othermay not easily satisfy the above-mentioned requirement.

As an LED module for an LED channel letter, a structure in which apackage level or chip level of LED is mounted on a circuit board such asa PCB is useful. In applying the LED module having the above-mentionedstructure to the LED channel letter, one should consider both theperformance of protecting the LED from external environment such ashumidity, or the like, and heat radiation performance of appropriatelyradiating heat generated from the LED.

Another object of the present invention is to provide an LED channelhaving an improved structure and an LED module appropriate for the LEDchannel.

Another object of the present invention is to provide an LED channelletter in which an improved heat radiation route is provided between anLED in an LED module and a channel having the LED module installedtherein and a route though which humidity, or the like, penetrates fromthe outside toward the LED in the LED module or a circuit board isreduced or block.

According to an exemplary embodiment of the present invention, there isprovided a method for manufacturing an LED module, the method including:disposing a circuit board at a molding space formed by an upper mold anda lower mold; adding a filling material to the molding space; hardeningthe filling material to form a molding cover covering at least a portionof an upper surface, a lower surface, and a side surface of the circuitboard, the molding cover having an opening exposing the lower surface ofthe circuit board; removing the upper mold and the lower mold from thecircuit board; and disposing an LED on the upper surface of the circuitboard.

According to another exemplary embodiment of the present invention,there is provided a light emitting diode (LED) module, including: acircuit board; an LED disposed on the circuit board; and a molding covercovering at least a portion of an upper surface, a lower surface, and aside surface of the circuit board. The molding cover has an opening atthe lower surface of the circuit board exposing the lower surface of thecircuit board.

According to still another exemplary embodiment of the presentinvention, there is provided a light emitting diode (LED) channelletter, including: a channel having two sidewalls and a bottompositioned between the two sidewalls; and a plurality of LED modulesdisposed on an upper surface of the bottom of the channel. Each of theplurality of LED modules comprises an LED, a circuit board having theLED disposed thereon, and a molding cover covering at least a portion ofan upper surface, a lower surface, and a side surface of the circuitboard, the molding cover having an opening at the lower surface of thecircuit board exposing the lower surface of the circuit board. Thechannel has a protrusion on the upper surface of the bottom thereof tobe inserted into the opening to contact the lower surface of the circuitboard.

According to still another exemplary embodiment of the presentinvention, there is provided a light emitting diode (LED) module,including: a circuit board comprising at least two holes; an LEDdisposed on the circuit board; and a molding cover covering at least aportion of an upper surface, a lower surface, and a side surface of thecircuit board. The molding cover extends into each of the at least twoholes without completely filling each of the at least two holes.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention, andtogether with the description serve to explain the principles of theinvention.

FIGS. 1A, 1B, 2, 3, and 4 are views that illustrate a process ofpreparing a circuit board and molding a molding cover on the circuitboard in a method for manufacturing an LED module according to anexemplary embodiment of the present invention.

FIG. 5 is a view that illustrates an LED which is mounted on the circuitboard having the molding cover formed thereon in the method formanufacturing an LED module according to the exemplary embodiment of thepresent invention.

FIG. 6 is a view describing an LED module after the LED is sealed by asealant in the method for manufacturing an LED module according to theexemplary embodiment of the present invention.

FIG. 7 is a bottom view that illustrates a lower surface of the LEDmodule shown in FIG. 6.

FIG. 8 is a bottom view that illustrates an LED module according toanother exemplary embodiment of the present invention.

FIGS. 9A to 9D are views that illustrate a method for manufacturing anLED module according to another exemplary embodiment of the presentinvention.

FIG. 10 is a plan view that partially illustrates an LED channel letteraccording to the exemplary embodiment of the present invention.

FIG. 11 is a cross-sectional view taken along the line I-I of FIG. 10.

FIG. 12 is a cross-sectional view taken along the line II-II of FIG. 10.

FIG. 13 is a bottom view of an LED module shown in FIGS. 10 to 12.

FIG. 14 is a cross-sectional view of a channel letter describing anotherexemplary embodiment of the present invention.

FIG. 15 is a plan view that illustrates an LED module according toanother exemplary embodiment of the present invention.

FIG. 16 is a cross-sectional view of the LED module taken along the lineI-I′ of FIG. 15.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Hereinafter, exemplary embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings. Theexemplary embodiments of the present invention to be described below areprovided by way of example so that the idea of the present invention canbe sufficiently transferred to those skilled in the art to which thepresent invention pertains. Therefore, the present invention is notlimited to the exemplary embodiments set forth herein but may bemodified in many different forms.

In the drawings, the thickness of layers, films, panels, regions, etc.,may be exaggerated for clarity. It will be understood that when anelement or layer is referred to as being “on” or “connected to” anotherelement or layer, it can be directly on or directly connected to theother element or layer, or intervening elements or layers may bepresent. In contrast, when an element is referred to as being “directlyon” or “directly connected to” another element or layer, there are nointervening elements or layers present. In contrast, It will beunderstood that when an element such as a layer, film, region, orsubstrate is referred to as being “beneath” another element, it can bedirectly beneath the other element or intervening elements may also bepresent. Meanwhile, when an element is referred to as being “directlybeneath” another element, there are no intervening elements present.

Hereinafter, exemplary embodiments of the present invention will beexplained in detail with reference to the accompanying drawings.

FIGS. 1 to 5 are views that illustrate a method for manufacturing an LEDmodule according to an exemplary embodiment of the present invention,wherein FIGS. 1 to 4 illustrate a process of preparing a circuit boardand covering a molding cover on the circuit board, and FIG. 5illustrates an LED which is mounted on the circuit board having themolding cover formed thereon. FIG. 6 illustrates an LED modulecompletely manufactured through a process of finally sealing the LEDwith a sealant. FIG. 7 is bottom view that illustrates a lower surfaceof the LED module shown in FIG. 6.

In order to manufacture an LED module according to an exemplaryembodiment of the present invention, a circuit board 2000 is firstprepared as shown in FIGS. 1A and 1B. FIGS. 1A and 1B are, respectively,a plan view of a prepared circuit board 2000 and a cross-sectional viewof the circuit board 2000 taken along the line I-I of FIG. 1A.

As shown in FIG. 1, two vertical penetrating pin holes 2100 may beformed through the circuit board 2000. The pin holes 2100 serve tostably maintain the circuit board 2000 within a mold when they areinserted into pins installed on the mold as described in detail below.In the present embodiment, the two pin holes 2100 are formed to faceeach other in a diagonal direction. The diagonal disposition of the pinholes 2100 and the pins inserted into the pin holes 2100 allows thecircuit board 2000 to be stably supported even with a small number ofpin holes and/or pins. The present invention is not limited to thespecific number of pin holes. According to the present embodiment, thecircuit board 2000 is a printed circuit board (PCB) to mount a lightemitting diode (LED) thereon. Although not shown, the circuit board 2000may include circuit patterns formed thereon, wherein the circuitpatterns include electrode patterns. The circuit board 2000 may be ametal PCB (MPCB) or a metal core PCB (MCPCB) based on a metal havingexcellent thermal conductivity.

As shown in FIG. 2, the circuit board 2000 is disposed at a moldingspace 103 of a mold that includes an upper mold 101 and a lower mold102. Two pins 104 are installed at a lower portion of the mold, that is,on the lower mold 102.

Each of the pins 104 may be variable type pins that may be advanced andretracted vertically in the molding space 103. A pressing scheme and ascrew conveying scheme are exemplary schemes of driving the variabletype pin. It is noted that although the variable type pins are used inthe present embodiment, fixed type pins which are fixedly installed onthe mold may also be used.

Each of the pins 104 has a tip portion 104 a, and a support end portion104 b positioned under the tip portion 104 a and having across-sectional area wider than that of the tip portion 104 a. The pins104 are inserted into the pin holes 2100 formed in the circuit board2000 to stably support the circuit board 2000 horizontally in the centerwithin the molding space 103. Here, the tip portion 104 a is not limitedto a certain height. Rather, the tip portion 104 a just needs to be highenough to be inserted into the pin hole 2100 in such a manner that itstably holds the circuit board but not so high that it is flush with theupper surface of the circuit board 2000. In this way, the molding cover3000, which will be described afterwards, can extend to a point justbelow the upper surface of the circuit board 2000 to a point just abovethe lower surface of the circuit board 2000.

In addition, the lower mold 102 has a protrusion 102 a shape configuredto be in contact with a lower surface of the circuit board 2000 andhaving a substantially rectangular cross section. In addition, the uppermold 101 has a substantially truncated conical protrusion 101 a shapeconfigured to be in contact with a central area of an upper surface ofthe circuit board 2000, on which an LED is to be mounted.

The protrusion 102 a formed at a lower portion of the molding space 103is provided so that a molding cover partially exposes the lower surfaceof the circuit board 2000 for heat radiation. Here, the protrusion 102 aformed at the lower portion of the molding space 103 also serves to helpthe pins 104 to support the circuit board 2000. If the molding cover isformed over the entire surface of the circuit board 2000, the protrusion102 a formed at the lower portion of the molding space 103 may beomitted. In addition, the protrusion 101 a formed at an upper portion ofthe molding space 103 is provided to form a cavity through which the LEDmay be mounted on the circuit board 2000 in a subsequent process. Thetruncated conical shape of the protrusion 101 a allows an inner wallsurface of the cavity to be an inclined reflective surface.

The tip portions 104 a of the pins 104 are inserted into the pin holes2100 of the circuit board 2000, and the support end portions 104 bthereof are configured to be in contact with the lower surface of thecircuit board 2000. Here, the tip portion 104 a is inserted in only aportion of a lower portion of the pin hole 2100, and a remaining spaceof an upper portion of the pin hole 2100 is to be filled with a plasticresin which forms a molding cover when the molding cover is formed.

As shown in FIG. 3, the molding space 103 is filled with a fillingmaterial such as a liquid or gel plastic resin P. The filling materialis then hardened in the molding space 103 to constitute the moldingcover which partially covers the upper surface and the lower surface,and sides of the circuit board 2000. The plastic resin P to form themolding cover is filled in an upper space of the pin hole 2100 to closethe pin hole 2100. For discrimination, “P” is used as a reference symbolthat indicates the plastic resin, and “3000” is used as a referencenumeral that indicates the molding cover formed of the plastic resin.

Thereafter, the upper mold 101 and the lower mold 102 are removed fromthe circuit board 2000. When the molding as shown in FIGS. 2 and 3, morespecifically, insert injection molding is completed, the molding cover3000 as shown in FIG. 4 is formed. This molding cover 3000 partiallycovers the upper surface and the lower surface, and the sides of thecircuit board 2000. The molding cover 3000 may include a cavity 3100formed on an upper surface thereof that conforms to the shape of theupper portion of the molding space described above, and a heat radiationhole 3200 formed on a lower surface thereof that conforms to the shapeof the lower portion of the molding space described above. In addition,the molding cover 3000 may include a connector housing portion 3300formed at a side thereof.

The cavity 3100 is formed on the upper surface of the circuit board2000, that is, at an area at which the LED is to be mounted, and has aninclined reflective surface. In addition, the heat radiation hole 3200exposes the circuit board 2000. In addition, the pin hole 2100 formed inthe circuit board 2000 is closed by a portion of the molding cover 3000.

Referring to FIG. 5, an LED 4000 is mounted in the cavity 3100. The LED4000 may be a package level of LED, that is, an LED package, or a chiplevel of LED, that is, an LED chip. Referring to FIG. 6, alight-transmitting sealant 5000 to protect the LED 4000 may be formedwith a substantially lens shape. According to the present embodiment,the sealant 5000 has a substantially hemispherical shape in which awidest portion of a lower portion thereof covers edges of a lowersurface of the cavity 3100. Through the above-mentioned process,manufacturing of the LED module 1000 as shown in FIG. 6 is completed.

Referring to FIG. 7, in the LED module, the heat radiation hole 3200 isformed to have a substantially rectangular shape at the lower surface ofthe molding cover 3000, and the lower surface of the circuit board 2000is exposed to the heat radiation hole 3200. Two pin marks 3500 areformed to face each other diagonally with the heat radiation hole 3200interposed therebetween. These two pin marks 3500, which are pin marksremaining after the pins that were used at the time of molding areseparated, are formed to match the pin holes 2100 (See FIG. 6) formed inthe circuit board 2000.

FIG. 8 is a bottom view that illustrates an LED module according toanother exemplary embodiment of the present invention. Referring to FIG.8, the LED module has a channel shape in which two opposite sides of theheat radiation hole 3200 formed at a lower surface of the molding cover3000 are opened and connected to their respective positions at whichthey are in contact with the two sides of the molding cover 3000.

FIGS. 9A to 9D are views that illustrate a method for manufacturing anLED module according to another exemplary embodiment of the presentinvention.

First, as shown in FIG. 9A, a package level or chip level of LED 4000 ismounted on an upper surface of a circuit board 2000. Then, as shown inFIG. 9B, a light-transmitting sealant 5000 having a hemispherical lensportion 5100 and a ring shaped edge portion 5200 in the vicinity of thehemispherical lens portion 5100 is formed to cover the LED 4000.Thereafter, as shown in FIG. 9C, a molding cover 3000 to partially coveran upper surface and a lower surface, and sides of the circuit board2000 is formed by, for example, insert injection molding, except for acavity 3100 to expose the light-transmitting sealant 5000 and a heatradiation hole 3200 to partly expose an area of a lower surface of thecircuit board 2000. Since a lower portion of the cavity of the moldingcover 3000 has a size smaller than that of the ring shaped edge portion5200, the molding cover 3000 is surface-bonded to an upper surface ofthe edge portion 5200. The molding cover 3000 and the sealant 5000 maybe formed of the same material having a difference only in terms oftransparency or plastic resin materials having a similar physicalproperty to improve adhesion between the molding cover 3000 and thesealant 5000.

According to the present embodiment, the molding cover 3000 is molded ina molding space 103 defined by an upper mold 101 and a lower mold 102,and pins 104 are used in order to stably maintain the circuit board 2000at the center of the molding space 103. Each of the pins 104 has a tipportion 104 a and a support end portion 104 b, wherein the tip portion104 a is inserted into a portion of a lower portion of the pin hole 2100formed in the circuit board 2000 and the support end portion 104 b is incontact with the circuit board 2000 to support the circuit board 2000. Ashape of the cavity 3100 and a shape of the heat radiation hole 3200 aredetermined by shapes of the upper and lower portions 101 a and 102 a ofthe molding space 103.

An LED module 1000 separated from the mold is shown in FIG. 9D.Describing the LED module 1000 once again with reference to FIG. 9D, theLED 4000 is mounted in an LED mounting area on the upper surface of thecircuit board 2000, and the sealant 5000 to cover the LED 4000 is formedat substantially the center of the upper surface of the circuit board2000. The molding cover 3000 partially covers the upper surface and thelower surface, and sides of the circuit board 2000. The molding cover3000 may include the cavity 3100 to correspond to the LED mounting areato thereby expose the LED 4000 and the sealant 5000, and the heatradiation hole 3200 partly exposes an area of the center of the lowersurface of the circuit board 2000. In the present embodiment, thesealant 5000 has a central lens portion 5100 and an edge portion 5200 inthe vicinity of the central lens portion 5100, and the molding cover3000 is formed after the sealant 5000 is formed, such that a portion ofa lower surface of the molding cover 3000 is bonded to an upper surfaceof the edge portion 5200. A portion of the lower surface of the moldingcover 3000 surface-contacts a portion of the sealant 5000, that is, theupper surface of the edge portion 5200, such that a reliable interfaceis secured between the sealant 5000 and the molding cover 3000. Thisinterface reduces the likelihood of infiltration of humidity or moistureinto the LED 4000 or the surrounding area of the LED 4000 through a gapbetween the sealant 5000 and the molding cover 3000.

An upper portion of the pin hole 2100 is also closed by a portion of themolding cover 3000.

FIG. 10 is a plan view that partially illustrates an LED channel letteraccording to the exemplary embodiment of the present invention; FIG. 11is a cross-sectional view taken along the line I-I of FIG. 10; FIG. 12is a cross-sectional view taken along the line II-II of FIG. 10; andFIG. 13 is a bottom view of an LED module shown in FIGS. 10 to 12.

As shown in FIGS. 10 to 12, an LED channel letter 1 according to theexemplary embodiment of the present invention may include an upper opentype channel 2 having a substantially “X” shaped plane and a pluralityof LED modules 1000 disposed in the channel 2. Although not shown, alight diffusion member including a light-transmitting plastic plate or alight-transmitting glass to cover an upper portion of the channel 2and/or a light-transmitting resin filled in an inner portion of thechannel 2 may be provided.

The present embodiment is not limited to a plane shape of the channelletter 1 shown in FIG. 10. That is, the channel letter 1 may havevarious shapes according to a letter, a logo, a symbol, a number, and/ora sign that is to be implemented.

According to the present embodiment, the channel 2 may include a pair ofsidewalls 21 and 21 facing each other and a bottom 22 positioned betweenthe sidewalls. In addition, a band shaped protrusion 24 may be disposedon an upper surface of the bottom 22 of the channel 2 in a directionthat is in parallel with the sidewalls 21 and 21. The protrusion 24 maybe formed by attaching a band shaped member having a certain length andthickness to the upper surface of the bottom 22 of the channel 2.Alternatively, the protrusion 24 may be formed integrally with thebottom of the channel 2 by press processing during a process ofmanufacturing the channel 2 or a process before or after the process ofmanufacturing the channel 2. The protrusion 24, which is provided at aheat radiation path between the LED module 1000 and the channel 2, mayhave high thermal conductivity, as described in detail below.

As shown in FIGS. 11 and 12, the LED module 1000 may include a circuitboard 2000, an LED 4000 mounted on the circuit board 2000, and a moldingcover 3000 disposed to partially cover an upper surface and a lowersurface, and sides of the circuit board 2000. Here, the molding cover3000 may include a cavity 3100 formed at a partial area of an uppersurface thereof to expose the LED 4000, and a heat radiation hole 3200formed at a partial area of a lower surface thereof to expose a lowersurface of the circuit board 2000.

Further, the LED module 1000 may include a light-transmitting sealant5000 molded inside the cavity 3100 so as to protect the LED 4000. Thissealant 5000 may be formed on the upper surface of the circuit board2000 so as to cover the LED 4000 before the molding cover 3000 isformed.

The sealant 5000 has a substantially hemispherical central lens portion5100 and a ring shape edge portion 5200 in the vicinity of the lensportion 5100. The sealant 5000 is formed to correspond to a position ofthe cavity 3100 of the molding cover 3000 before the molding cover 3000is formed. The ring shape edge portion 5200 may be formed to have awidth wider than that of a lower portion of the cavity 3100 having aninclined structure. When the molding cover 3000 is formed, the moldingcover 3000 is partially surface-bonded to an upper surface of the ringshaped edge portion 5200.

Therefore, the molding cover 3000 and the sealant 5000 cover almost theentire circuit board 2000 except for the heat radiation hole 3200 in apartial area of a lower surface of the molding cover 3000, whichsignificantly reduces external humidity infiltrating into thesurrounding area of the LED 4000 through the circuit board 2000.

Meanwhile, the molding cover 3000 and the sealant 5000 may be formed ofthe same or similar plastic material to improve adhesion between themolding cover 3000 and the sealant 5000. According to the presentembodiment, the molding cover 3000 and the sealant 5000 may be formed ofthe same plastic material, wherein dye or pigment such as a white color,a silver-white color, a silver color, or the like, to improvereflectivity is added to the plastic resin that forms the molding cover3000.

Meanwhile, when the plurality of LED module 1000 are mounted on theupper surface of the bottom 22 of the channel 2, the band shapedprotrusion 24 fixedly disposed on the upper surface of the bottom 22 isinserted into the heat radiation hole 3200 formed at the lower surfaceof the molding cover 3000. At this time, the protrusion 24 contacts thecircuit board 2000 exposed by the heat radiation hole 3200.

The LED module 1000 may further include a circuit part 6000. The circuitpart 6000 may be positioned in the molding cover 3000 and may be mountedon the circuit board 2000. Here, the circuit part 6000 is not limited tobeing mounted on the circuit board 2000, but may also be mounted on aseparate driving circuit board (not shown) positioned at an edge of thecircuit board 2000. The circuit part 6000 may include a plurality ofdriving elements and may be mounted along the edge of the circuit board2000.

As shown in FIG. 13, the heat radiation hole 3200 may extend from anedge of the lower surface of the molding cover 3000 to an opposite edgeso as to correspond to the shape of the protrusion 24. Therefore, theheat radiation hole 3200 has a channel shape in which both sides thereofare opened laterally at the lower surface of the molding cover 3000. Inaddition, the entire upper surface of the protrusion 24 may be a planeso as to increase a contact area with a flat lower surface of thecircuit board 2000. Through the structure in which the both sides of theheat radiation hole 3200 are opened, several heat radiation holesincluded in several LED modules may be inserted to an elongateprotrusion 24.

The configuration of the channel letter 1 described above forms a heatradiation route from the LED 4000 in the LED module 1000 to the outsidethrough the circuit board 2000 and the protrusion 24 and the channel 2that contact the circuit board 2000, as shown in FIGS. 11 and 12.Through this heat radiation route, heat generated from the LED 4000 maybe efficiently radiated to the outside of the channel letter 1.

Referring to FIG. 10, the LED module 1000 has a substantiallyrectangular shape and includes four connectors 3300 installed on each offour sides. Each of the connectors 3300 are installed on each of thesides of the LED module 1000, particularly, the molding cover 3000,thereby making it possible to easily implement a complicated channelletter such an “X” shape shown in FIG. 10 and to simplify an operationof disposing the LED modules in the channel having the complicated shapeand connecting the LED modules to each other using wires 7.

According to the present embodiment, vertically intersecting four linearunit channels are collected to configure an “X” shaped channel 2. TheLED module 1000 installed in an intersecting area of the four unitchannels, that is, a central area of the channel 2 utilizes all of thefour connectors 3300, and remaining LED modules 1000 utilize only twoconnectors or one connector 3300.

The LED module 1000 according to the present embodiment may have arectangular shape with four sides and a total of four connectorsprovided on each of the four sides. However, the LED module 1000 mayhave three, four, five, six, or more connectors according to whether ithas a triangular shape, a rectangular shape, a pentagonal shape, ahexagonal shape, or other polygonal shapes.

The LED module 1000 used in the LED channel 2 may be manufactured by themethod for manufacturing an LED module described with reference to FIGS.1 to 6 or the method for manufacturing an LED module described withreference to FIGS. 9A to 9D.

FIG. 14 is a cross-sectional view of a channel letter describing anotherexemplary embodiment of the present invention.

Referring to FIG. 14, a channel letter 1 may include a plurality ofprotrusions 24 formed on an upper surface of a bottom 22 of a channel 2and having a block shape, and an LED module 1000 may include a heatradiation hole 3200 formed to expose a lower surface of a circuit board2000, similar to the above-mentioned embodiment. The heat radiation hole3200 has a shape corresponding to that of the protrusion 24 of thechannel letter 1 to be inserted into the protrusion 24. In addition,each of the protrusions 24 is inserted into the heat radiation hole 3200to contact the lower surface of the circuit board 2000. According to thepresent embodiment, the LED channel letter 1 may include a plurality ofLED modules 1000 disposed therein, wherein each of the plurality of LEDmodules 1000 is fixedly maintained on the upper surface of the bottom 22of the channel 2 by inserting the heat radiation hole 3200 into theprotrusion 24. In addition, the heat radiation hole 3200 and theprotrusion 24 provide a heat radiation route from the inside of the LEDmodule 1000 to the outside thereof.

The LED module 1000 may further include a circuit part 6000. The circuitpart 6000 may be positioned in the molding cover 3000 and may be mountedon the circuit board 2000. The circuit part 6000 is not limited to beingmounted on the circuit board 2000, but may also be mounted on a separatedriving circuit board (not shown) positioned at an edge of the circuitboard 2000. The circuit part 6000 may include a plurality of drivingelements and may be mounted along the edge of the circuit board 2000.

According to the exemplary embodiments of the present invention, themolding cover formed by molding with a mold covers the upper surface,the lower surface, and the sides of the circuit board, thereby making itpossible to better protect the electrode, the LED, and the like, on thecircuit board from humidity and/or air of an external environment. Inaddition, the penetration pin hole of the circuit board that has beenused together with the pin of the mold in order to maintain the circuitboard at the center of the molding space is closed with a portion of themolding cover, thereby making it possible to prevent penetration ofhumidity or external air through the pin hole of the circuit board.

FIG. 15 is a plan view that illustrates an LED module 1002 according toanother exemplary embodiment of the present invention, and FIG. 16 is across-sectional view of the LED module 1002 taken along the line I-I′ ofFIG. 15.

As shown in FIGS. 15 and 16, the LED module 1002 includes a circuitboard 2000, a plurality of LEDs 4000, a molding cover 3000, and acircuit part 6000.

The LEDs 4000 are mounted at the center of the circuit board. The centerof the circuit board 2000 may be referred to as a mounting area. Throughholes 2100 are formed at edges of the mounting area. The through holes2100 extend through the circuit board 2000 and may be referred to as pinholes.

The LEDs 4000 are mounted in the mounting area positioned at the centerof the circuit board 2000.

The molding cover 3000 may cover edges of the circuit board 2000 and maybe spaced apart from the LEDs 4000 by a predetermined gap. The moldingcover 3000 may contact upper and lower surfaces of the circuit board2000 at the edges of the circuit board 2000. The molding cover 3000 mayinclude an insulating space 3001 formed therein. The insulating space3001 may provide a space in which the circuit part 6000 may be mounted.

The circuit part 6000 may be positioned in the insulating space 3001 andmay be mounted on the circuit board 2000. The circuit part 6000 mayinclude driving elements and may be positioned along the edge of thecircuit board 2000. The circuit part 6000 may be spaced apart from thepin hole 2100 by a predetermined gap. Here, the circuit part 6000 is notlimited to being mounted on the circuit board 2000, but may be mountedon a separate driving circuit board (not shown) and electricallyconnected to the circuit board 2000 through a separate connectionstructure. The connection structure is not particularly limited, but maybe, for example, a structure in which a concave part positioned in aninner surface of the driving circuit board and a protrusion protrudingon an outer surface of the circuit board 2000 contact each other.

In the LED module 1002, the circuit part 6000 is mounted at the edge ofthe circuit board 2000, such that the driving circuit may be embedded.Therefore, the LED module 1000 may be provided in a compact form. Inaddition, the LED 4000 and the circuit part 6000 are spatially separatedfrom each other, such that heat transfer between the LED 4000 and thecircuit part 6000 is reduced, thereby making it possible to prevent adecrease in reliability due to heat.

According to the exemplary embodiments of the present invention, whenthe LED module having the connector for connecting a power supply or acircuit is applied to the LED channel letter, in case a problem occursin a specific LED module, the channel letter may be used by replacingonly a corresponding LED module, which is economically practical.Further, the LED channel letter according to the exemplary embodiment ofthe present invention may implement a complicated letter, logo, symbol,number, and/or sign. Particularly, the LED module according to theexemplary embodiment of the present invention is excellent in view ofperformance of protecting the LED from the external environment such ashumidity, or the like, and heat radiation performance of appropriatelyradiating heat generated from the LED, such that the LED module may beusefully used for the LED channel letter.

What is claimed is:
 1. A light emitting diode (LED) module comprising: acircuit board having an upper surface and a lower surface, the circuitboard comprising first and second through holes arranged at oppositecorners of the circuit board and extending from the upper surface to thelower surface; a plurality of LEDs centrally disposed on the uppersurface of the circuit board; a circuit part disposed on a peripheralportion of the circuit board to surround the plurality of LEDs; amolding cover spaced entirely apart from the plurality of LEDs andextending from the upper surface to the lower surface of the circuitboard; and a light transparent sealant covering the plurality of LEDs,wherein: an upper portion of the molding cover is disposed on the uppersurface of the circuit board to cover the circuit part; a portion of theupper portion of the molding cover arranged between the plurality ofLEDs and the circuit part has a constant thickness and is inclined tothe upper surface of the circuit board; and an edge portion of the lighttransparent sealant is bonded to a lower end surface of the upperportion of the molding cover that faces the plurality of LEDs.
 2. TheLED Module of claim 1, wherein a portion of the molding cover isdisposed in the first and second through holes.
 3. The LED module ofclaim 2, wherein the circuit part and the first and second through holesare disposed adjacent to an edge of the circuit board and are spacedapart from one another.
 4. The LED module of claim 2, wherein the upperportion of the molding cover extends downwardly to completely fill anupper space of the first and second through holes.
 5. The LED module ofclaim 1, wherein the molding cover and the light transparent sealant aremade of similar materials having the same physical property except for atransparency.
 6. The LED module of claim 1, wherein the molding coverand the light transparent sealant are made of plastic resin materialshaving a similar physical property.
 7. The LED module of claim 1,wherein the edge portion of the light transparent sealant is overlappedwith the lower end surface of the upper portion of the molding cover. 8.The LED module of claim 7, wherein the light transparent sealant has ahemispherical shape, a widest portion of which covers the lower endsurface of the upper portion of the molding cover.
 9. The LED module ofclaim 7, wherein the light transparent sealant further comprises acentral lens portion, and the edge portion of the light transparentsealant is positioned in the vicinity of the central lens portion.